The United States announced Sunday it will deploy troops and an advanced anti-missile system to Israel to strengthen its air defenses after missile strikes from Iran.

U.S. President Joe Biden said the move was meant "to defend Israel," which is weighing an expected retaliation against Iran after Tehran fired more than 180 missiles at Israel on Oct 1.

The United States has been privately urging Israel to calibrate its response to avoid triggering a broader war in the Middle East, officials say, with Biden publicly voicing his opposition to an Israeli attack on Iran's nuclear sites and his concerns about a strike on Iran's energy infrastructure.

Pentagon spokesperson Maj. Gen. Patrick Ryder described the deployment as part of "the broader adjustments the U.S. military has made in recent months" to support Israel and defend U.S. personnel from attacks by Iran and Iranian-backed groups.

But a U.S. military deployment to Israel is rare outside of drills, given Israel's own military capabilities. U.S. troops in recent months have aided Israel's defense from warships and fighter jets in the Middle East when it came under Iranian attack.

But they were based outside of Israel.

The Terminal High Altitude Area Defense system, or THAAD, is a critical part of the U.S. military's layered air defense systems and adds to Israel's already formidable anti-missile defenses.

A THAAD battery usually requires about 100 troops to operate. It counts six truck mounted launchers, with eight interceptors on each launcher, and a powerful radar.

Iran's Foreign Minister Abbas Araqchi warned earlier on Sunday that the United States was putting the lives of its troops "at risk by deploying them to operate U.S. missile systems in Israel."

"While we have made tremendous efforts in recent days to contain an all-out war in our region, I say it clearly that we have no red lines in defending our people and interests," Araqchi posted on X. Still, experts say Iran has sought to avoid a direct war with the United States, making deployment of U.S. forces to Israel another factor in its calculus going forward.